Carefully access the potentiometer giving you trouble, should look similar to this:

… and release 1-2 drops of FaderLube into a hole in the case. Then turn the knob completely back and forth 10 times, and reassemble.

My Blackstar Ht-Dual distortion pedal developed noisy pots, and I put 1-2 drops in each rectangular hole atop the white plastic housing of the potentiometers. After turning the knobs, then reassembling, the pedal was good as new.

Take note that DeOxit has other products (D5, DN5, D100) meant for cleaning contacts and switches. DO NOT use these on potentiometers, as they will eat away the carbon track inside that the sliding contact rides on. FaderLube linked above is non corrosive and is the safest of all DeOxit products to use on pots and sliding faders.